forked from TrueCloudLab/restic
7d12c29286
This unified construction removes most backend-specific code from global.go. The backend registry will also enable integration tests to use custom backends if necessary.
323 lines
8 KiB
Go
323 lines
8 KiB
Go
package b2
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import (
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"context"
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"hash"
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"io"
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"net/http"
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"path"
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"sync"
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"time"
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"github.com/restic/restic/internal/backend"
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"github.com/restic/restic/internal/backend/layout"
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"github.com/restic/restic/internal/backend/location"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/restic"
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"github.com/kurin/blazer/b2"
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"github.com/kurin/blazer/base"
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)
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// b2Backend is a backend which stores its data on Backblaze B2.
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type b2Backend struct {
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client *b2.Client
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bucket *b2.Bucket
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cfg Config
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listMaxItems int
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layout.Layout
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canDelete bool
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}
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// Billing happens in 1000 item granlarity, but we are more interested in reducing the number of network round trips
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const defaultListMaxItems = 10 * 1000
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// ensure statically that *b2Backend implements restic.Backend.
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var _ restic.Backend = &b2Backend{}
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func NewFactory() location.Factory {
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return location.NewHTTPBackendFactory(ParseConfig, location.NoPassword, Create, Open)
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}
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type sniffingRoundTripper struct {
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sync.Mutex
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lastErr error
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http.RoundTripper
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}
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func (s *sniffingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
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res, err := s.RoundTripper.RoundTrip(req)
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if err != nil {
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s.Lock()
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s.lastErr = err
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s.Unlock()
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}
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return res, err
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}
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func newClient(ctx context.Context, cfg Config, rt http.RoundTripper) (*b2.Client, error) {
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sniffer := &sniffingRoundTripper{RoundTripper: rt}
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opts := []b2.ClientOption{b2.Transport(sniffer)}
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// if the connection B2 fails, this can cause the client to hang
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// cancel the connection after a minute to at least provide some feedback to the user
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ctx, cancel := context.WithTimeout(ctx, time.Minute)
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defer cancel()
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c, err := b2.NewClient(ctx, cfg.AccountID, cfg.Key.Unwrap(), opts...)
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if err == context.DeadlineExceeded {
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if sniffer.lastErr != nil {
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return nil, sniffer.lastErr
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}
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return nil, errors.New("connection to B2 failed")
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} else if err != nil {
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return nil, errors.Wrap(err, "b2.NewClient")
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}
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return c, nil
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}
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// Open opens a connection to the B2 service.
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func Open(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) {
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debug.Log("cfg %#v", cfg)
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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client, err := newClient(ctx, cfg, rt)
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if err != nil {
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return nil, err
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}
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bucket, err := client.Bucket(ctx, cfg.Bucket)
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if err != nil {
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return nil, errors.Wrap(err, "Bucket")
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}
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be := &b2Backend{
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client: client,
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bucket: bucket,
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cfg: cfg,
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Layout: &layout.DefaultLayout{
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Join: path.Join,
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Path: cfg.Prefix,
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},
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listMaxItems: defaultListMaxItems,
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canDelete: true,
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}
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return be, nil
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}
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// Create opens a connection to the B2 service. If the bucket does not exist yet,
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// it is created.
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func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) {
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debug.Log("cfg %#v", cfg)
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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client, err := newClient(ctx, cfg, rt)
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if err != nil {
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return nil, err
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}
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attr := b2.BucketAttrs{
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Type: b2.Private,
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}
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bucket, err := client.NewBucket(ctx, cfg.Bucket, &attr)
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if err != nil {
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return nil, errors.Wrap(err, "NewBucket")
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}
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be := &b2Backend{
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client: client,
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bucket: bucket,
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cfg: cfg,
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Layout: &layout.DefaultLayout{
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Join: path.Join,
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Path: cfg.Prefix,
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},
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listMaxItems: defaultListMaxItems,
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}
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_, err = be.Stat(ctx, restic.Handle{Type: restic.ConfigFile})
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if err != nil && !be.IsNotExist(err) {
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return nil, err
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}
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if err == nil {
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return nil, errors.New("config already exists")
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}
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return be, nil
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}
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// SetListMaxItems sets the number of list items to load per request.
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func (be *b2Backend) SetListMaxItems(i int) {
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be.listMaxItems = i
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}
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func (be *b2Backend) Connections() uint {
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return be.cfg.Connections
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}
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// Location returns the location for the backend.
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func (be *b2Backend) Location() string {
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return be.cfg.Bucket
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}
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// Hasher may return a hash function for calculating a content hash for the backend
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func (be *b2Backend) Hasher() hash.Hash {
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return nil
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}
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// HasAtomicReplace returns whether Save() can atomically replace files
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func (be *b2Backend) HasAtomicReplace() bool {
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return true
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}
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// IsNotExist returns true if the error is caused by a non-existing file.
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func (be *b2Backend) IsNotExist(err error) bool {
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// blazer/b2 does not export its error types and values,
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// so we can't use errors.{As,Is}.
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for ; err != nil; err = errors.Unwrap(err) {
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if b2.IsNotExist(err) {
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return true
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}
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}
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return false
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}
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// Load runs fn with a reader that yields the contents of the file at h at the
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// given offset.
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func (be *b2Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
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}
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func (be *b2Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
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name := be.Layout.Filename(h)
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obj := be.bucket.Object(name)
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if offset == 0 && length == 0 {
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return obj.NewReader(ctx), nil
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}
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// pass a negative length to NewRangeReader so that the remainder of the
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// file is read.
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if length == 0 {
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length = -1
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}
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return obj.NewRangeReader(ctx, offset, int64(length)), nil
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}
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// Save stores data in the backend at the handle.
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func (be *b2Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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name := be.Filename(h)
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obj := be.bucket.Object(name)
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// b2 always requires sha1 checksums for uploaded file parts
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w := obj.NewWriter(ctx)
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n, err := io.Copy(w, rd)
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if err != nil {
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_ = w.Close()
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return errors.Wrap(err, "Copy")
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}
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// sanity check
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if n != rd.Length() {
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return errors.Errorf("wrote %d bytes instead of the expected %d bytes", n, rd.Length())
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}
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return errors.Wrap(w.Close(), "Close")
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}
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// Stat returns information about a blob.
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func (be *b2Backend) Stat(ctx context.Context, h restic.Handle) (bi restic.FileInfo, err error) {
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name := be.Filename(h)
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obj := be.bucket.Object(name)
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info, err := obj.Attrs(ctx)
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if err != nil {
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return restic.FileInfo{}, errors.Wrap(err, "Stat")
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}
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return restic.FileInfo{Size: info.Size, Name: h.Name}, nil
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}
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// Remove removes the blob with the given name and type.
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func (be *b2Backend) Remove(ctx context.Context, h restic.Handle) error {
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// the retry backend will also repeat the remove method up to 10 times
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for i := 0; i < 3; i++ {
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obj := be.bucket.Object(be.Filename(h))
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var err error
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if be.canDelete {
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err = obj.Delete(ctx)
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if err == nil {
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// keep deleting until we are sure that no leftover file versions exist
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continue
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}
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code, _ := base.Code(err)
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if code == 401 { // unauthorized
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// fallback to hide if not allowed to delete files
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be.canDelete = false
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debug.Log("Removing %v failed, falling back to b2_hide_file.", h)
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continue
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}
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} else {
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// hide adds a new file version hiding all older ones, thus retries are not necessary
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err = obj.Hide(ctx)
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}
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// consider a file as removed if b2 informs us that it does not exist
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if b2.IsNotExist(err) {
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return nil
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}
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return errors.Wrap(err, "Delete")
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}
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return errors.New("failed to delete all file versions")
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}
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// List returns a channel that yields all names of blobs of type t.
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func (be *b2Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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prefix, _ := be.Basedir(t)
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iter := be.bucket.List(ctx, b2.ListPrefix(prefix), b2.ListPageSize(be.listMaxItems))
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for iter.Next() {
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obj := iter.Object()
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attrs, err := obj.Attrs(ctx)
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if err != nil {
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return err
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}
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fi := restic.FileInfo{
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Name: path.Base(obj.Name()),
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Size: attrs.Size,
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}
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if err := fn(fi); err != nil {
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return err
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}
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}
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return iter.Err()
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}
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// Delete removes all restic keys in the bucket. It will not remove the bucket itself.
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func (be *b2Backend) Delete(ctx context.Context) error {
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return backend.DefaultDelete(ctx, be)
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}
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// Close does nothing
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func (be *b2Backend) Close() error { return nil }
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